At $11/day this is much cheaper than taking a cab to and from the airport, or parking in the main airport garage at $24/day. And it’s fast, because the parking lot is on the Link train route, which means 5 minutes and you’re inside the terminal. Useful option for short trips out of Toronto.
Here’s the web page, and a map. You do need to print out and bring the coupon with you, otherwise its $14/day.
They also recently added a Cell Phone Lot for people to wait close by (sort of) until the passengers they’re waiting for have called to let them know they’ve arrived. There’s a map of the lot location at that link.
It’s better than paying $6/hr for the short-term parking lot, and better than hanging out on the shoulder of the roads leading up to the terminal.